Hydraulic slack take-up device



May 21, 1935. R. F. DOW

HYDRAULIC SLACK TAkE-UP DEVICE Filed May 6, 1932 VENTOR ATTORNEYS.

Patented May 21, .1935

n in 2,002,081

PATENT, orrrce 2,002,081 7 n v y HUDRAULIG iSL'ACK TAKE-UR "DEVICE "Richard F. Dow, Hartford,Conn assignorto "The Whitney f 'tion'of Connecticut fg. 00., Hartford, Conn, a corpora- Application :s, ,iaazgy-ssiiar-nb. 609 ,60;

sonims. (01574-24211 This invention relates to a novel andw improved form :of slack take-up device of the type d scribed and'claimed in my copending application, Serial No. 360,550, Patent .No. 1,913,872.

Thenovel features willbe'best understood from the following descriptionand the annexed drawing, inwhich I have shown a selected embodiment of the invention, and in which:

Mjlfig. .1 is a diagrammaticview of a chain drive having my invention employed therein.

Fig. 2 is a face view of the take-up device appearingin Fig. l. a i

Fig. 3 is a section on the line3-.3 of Fig. 2.

Fig. 4 is a section on the line 4 --4 of 3. l .The'invention finds particular utility in l connection with taking up of slack automatically in chain drives, such as used, for-example, in the operation of timing mechanism on automobiles.

For the sakeof simplicity, I will hereinafter refer to the device as used-withzasprocket andachain,

althoughI do not intend thereby tolimit myself to theluse of the invention witha chaindrive to theexclusion, of a belt or other drive where it may be founduseful. a y

. .Referring firsttoiFig. 1, I have indicated there irr :a' chain drive embodying a chain I engaging sprockets'on-ithreeshafts.2, 3 and '24. The slack maybe taken up bymydevice which-is indicated generally at 5 and :whichengages a loop 6 ofthe chain between the shafts 2 and 4 U O 1 .The device comprises a sprocket 'l 'provided with theusual teeth and forming anidler whichmay rotate upon a bearing 8 o-f-cylindrical form and WhiC'hxziS mounted upona; pivotformed of a: sleeve g 9 eccentrically disposed .withrrespect to the axis ofthe hearing. The sleeve 9 may be keyed as shown at, H) intoafixed bearing H and extends forwardly or to the right of Fig. 3 to supp rtthe movable-bearing '8. The sleeve may-be secured in place at therearthereof :by means of a screw 12 threaded. into the rearendof thesleeve s and having'itshead forcedagain'st a-washer" I 3 engaging the fixed bearing ll. .Thebearin'gmay be retained on the sleeve asby a washer l3'.and ac'o'tter pinfl3'fl:

1 As described and claimed'in myfaforesaid c0 pending application, the sleeve"9 is" provided with longitudinally extending slots 14 disposed coaxfially of the sleeve and through which enemas I6 of which are received inspiral grooves I1 .in'the inner cylindrical surface l8 ,of the bearingt. 'By thisarrangemennfiwhen the pin it moving towards the front or towards the .rlght o f'Fig. 3-,; the pin l5 will cause rotation of the-bearing in the direction of the arrow D in Securedto the sleeve is a flange E9, in the face of :whichare-aplurality of ratchet teeth formed bywrecesseslfi adapted to receive a pawl pin 2!. ,5 This pawl and ratchet arrangement normally pe mits rotation of thebearing 8 in the direction of the arrowD in Fig. 2,while preventing rotation thereof in the opposite direction. The pin 2| is slidably mounted in the bearing 8 and preferably is disposed substantiallyparallel to the axis of the pivot formed by the sleeve 9 andis normally urged towards the left of Fig. 3 asby a-compression spring .22. The pawl pin maybe provided with a handle 23 by means of whichit may be retracted, 15 and it also'may be provided with a transverse locking pin sliding in a groove in the bearing, so that the pawl pin may be held out of operative engagement with'the teeth on the flange I!) by retracting it to the right: of Fig. 3 and then turning it slightly on its axis untilthe pin 24 engages the faceof-the bearing 8.

The pin 15 is mountedon the-front end of a piston .25 which slides in the sleeve 9 as a cylinder. Preferablythe-pin is of the square cross section 25 shown in Fig. 3 in ordertdfit a correspondingly shaped slot in thefront end of the piston, and

the diagonally opposite corners of the pin are cut off "as-indicated in Figs. 3 and4 so as to fit the grooves I1. 'The piston is-operated by meansof hydraulic pressure supplied tothe space 26 at the rear; of :the piston, this pressure being preferably furnished byoil entering that space through an opening l'l in the wall of the cylinder from a supplyline 28. A suitable one-way;valve 29 is providedwhich has its head '30 engaging a seat 31 so as to prevent'escape of the liquid from" the space 26 while permitting it to pass into that space from theline 28. In caseit is desired to relieve the pressure formed by the liquid in the space 26, a suitable relief outlet is provided, here shown as being in the form of a plug 32 threaded into the fixed supportl l and holding a valve 33 'in place'against its seat, the seat communicating with the space 26. The plug 32 is provided with a central opening 32', and this opening communicates with. a slot 33 in the valve 33 so that upon loosening of the plug, oil may escape through the opening 32..

p .Preferably, the liquid used is oil, although, of

course, other liquids may beemployed where to the pump of the oil system of an automobile or may be connected to a separate supply of heavy grease of a semi-fluid consistency.

In operation, the pin 2| is first retracted and held out of engagement with the ratchet teeth formed by the recesses 26. Next, the piston 25 is forced to the left as viewed in Fig. 3 by means of a suitable tool which may enter the open end at the right of the sleeve 9. The relief outlet 32 may be opened for this purpose. The above op oration will cause rotation of the bearing 8 on the sleeve 9 in a direction opposite to that indicated by the arrows B and D in Figs. 1 and 2.

The pawl pin 2| is then released so that it may engage the ratchet teeth which will prevent furtherrotation of the bearing in the direction in which it has just been rotating. The outlet 32 is now closed and a liquid admitted to the space 25 to fill that space, this liquid tending to force the piston 25 to the right of Fig. 3 and thus to rotate the bearing 8 in the direction of the arrows B and D inFigs. 1 and 2. The chain I has its loop 6 trained over the portion of the sprocket l which has the greatest eccentricity with respect to the pivot 9 as shown in Fig. 1, and so long as the loop'S is tight, the bearing 8 will resist-rotation by movement of the piston 25. As slack occurs, however, rotation in the direction of the arrows Band D will take place,the pawl and ratchet arrangement described preventing return movement of any great amount, and return movement of any amount at all being resisted and substantially prevented by the hydraulic pressure exerted on the piston 25. I

The arrangement described has numerous advantages, among which is the fact that it provides a positive force for the rotation of the bearing 8 which can be readily designed for any given pressure by varying the size of the piston unit. If necessary and found desirable, it can be used without the inlet valve 29, but this valve is of utility particularly in case of back firing or any other situation which may arise in practice and which tends to cause reversal -of the direction in which the chain is moving. The chain is normally moving in the direction indicated by the arrow A in Fig. 1, andithat means that the sprocket 1 is rotating in the direction indicated by the arrow C in Fig. 2. Normally the bearing 8 is relatively stationary with respect to the sprocket, although it rotates to take up slack, as described above, the piston 25 moving towards the right of Fig. 3 to prevent any back movement and the oil or other liquid flowing into the space 26 to hold the piston towards the right in its forward position and to hold the pin l 5 tightly in the slots 14 and grooves 11. Forexample, ii the engine to which the drive of Fig. 1 is connected should back-fire, or if for some other reason the direction of movement of the chain should be reversed and then suddenly resume its movement in the normal direction, theresult would be to exert a sudden and violent force upon the piston 25, tending to force it towards the left of Fig. 3. While if a pump were used to force the oil into the space 26, this movement of the piston might be adequately resisted, nevertheless the valve 29 forms a positive means for. preventing movement of thepiston and for cushioning the shock of the reversal by means of the liquid in the space 26. This reverse movement of the bearing would, of course, be resisted by the pawl and ratchet arrangement limiting the movement to the distance between teeth of the ratchet, but the e I 2,002,081 The line 28 may, for example, be connected either valve 29 limits the movement to a much smaller amount, and in fact, to all intents and purposes, prevents any substantial movement of the piston.

The piston 25 is preferably unpacked in the cylinder, leaving a slight clearance between the cylinder and the piston, so that a certain amount of oil may pass along the surfaces thereof and find its way into the grooves l? andthence into oil passages 34 in the bearing and 35 in the sprocket. By this arrangement, the parts may be properly lubricated as well as operated to take up the slack.

-While I have shown the invention as embodied in a specific form, it is to be understood that various changes in details may be made without departing from the scope of the invention, and I therefore do not intend to limit myself except by the appended claims.

I claim: l

1. A slack take-up device comprising an idler adapted to engage a chain, a-bearing on which said idler is rotatably'mounted, a pivot supporting said bearing and disposed eccentrically to its axis, a pin movable lengthwise of said pivot, a connection between saidpin and bearing adapted to cause rotation of said bearing by said lengthwise movement of the pin, a piston operatively connected to said pin, a cylinder within which said piston is movably received, means to supply liquid under pressure to said cylinder to move said piston in one direction, and means to prevent backward fiow of said liquid from said cylinder, thereby preventing movement of said piston in the opposite direction.

2. A slack take-up device comprising an idler adapted. to engage a chain, a bearing on which said idler is rotatably mounted, a pivot supporting said bearing and disposed eccentrically to its axis, a pin movable lengthwise of said pivot, a connection between said pin and bearing adapted to cause rotation of said bearing by said lengthwise movement of the pin, a piston disposed coaxially of said pivot and having said pin secured thereto adjacent one end thereof, a cylinder in which said piston is adapted to slide, an inlet for liquid into said cylinder into a space beyond the other end of the piston, and means to maintain a sufiicient pressure on the liquid in said space to substantially prevent movement of the piston into said space.

3. A slack take-up device comprising an idler adapted toengage a chain, a bearing on which said idler is rotatably mounted, a pivot supporting said bearing and disposed eccentrically to its axis, a pin movable lengthwise of said pivot, a connection between said pin and bearing adapted to cause rotation of said bearing by said lengthwise movement of the pin, a piston disposed coaxially of said pivot and having said pin secured thereto adjacent one. end thereof, a cylinder in whichsaid piston is adapted to: slide, an inlet for liquid into said cylinder beyond the other end of the piston, and a valve preventing flow 'of the liquid out ofv the inlet.

4. A slack take-up device comprising an idler adapted to engage a chain, a bearing onwhich said idler is rotatably mounted, a pivot supporting-said bearing and disposed eccentrically to its axis, a pin movable lengthwise of said pivot, a connection between said pin and bearing adapted to cause rotation of said bearing by said lengthliquid into said cylinder beyond the other end of der adjacent said inlet.

5. A slack take-up device comprising an idler adapted to engage a chain, a bearing on which i said idler is rotatably mounted, a pivot supporting said bearing and disposedeccentrically to its axis, a pin movable lengthwise of said pivot, a connection between said pin and bearing adapted tocause rotation of said hearing by said lengthwise movement of the pin, a piston operatively connected to said pin, a cylinder receiving said piston, oil passages in said pivot and bearing and communicating with said cylinder, and means for supplying oil to said cylinder to actuate the piston, said piston and cylinder having a. slight clearance therebetween, whereby oil may work along the piston to said passages.

6. A slack take-up device comprising an idler adapted to engage a said idler is rotatably mounted, a pivot supporting said bearing and disposed eccentrically to its axis and in the form of a sleeve, a pin disposed in said sleeve and movable lengthwise thereof, a connection between said pin and bearing adapted to cause rotation of said bearing by said lengthwise movement of the pin, a piston operatively connected to said pin, a cylinder receiving said piston, oil passages in said pivot and bearing and leading from the interior of said sleeve to the contacting surfaces between the idler and the bearing, and means for supplying oil to said cylinder said piston and cylinder therebetween, whereby to actuate the piston, having a slight clearance oil may work along the piston into said sleeve and thence to said passages.

adapted to engage chain, a bearing on which piston operatively '7. -A slack take-up device comprising an idler adapted to engage a chain, a bearing on which said idler is rotatably mounted, a pivot supporting said bearing and disposed eccentrically to its axis and in the form of a sleeve, a pin disposed in said sleeve and movable lengthwise thereof, a connection between said pin and bearing adapted to cause rotation of said bearing by said lengthwise movement of the pin, a piston operatively connected to said pin, a cylinder receiving said piston, oil passages in said sleeve leading, from the interior thereof to the contacting surfaces between said bearing and pivot, and means for supplying oil to said cylinder to actuate the piston, said piston and cylinder having a slight clearance therebetween, whereby oil may work along the piston into said sleeve and thence to said passages.

8. A slack take-up device comprising an idler a chain, a bearing on which said idler is rotatably mounted, a pivot supporting said bearing and disposed eccentrically to its axis, a pin movable lengthwise of said pivot,

a connection between said pin and bearing adapted to cause rotation of said bearing in one direction by said lengthwise movement of the pin, a

connected to saidpin, a cylinder within which said piston is movably received, means to supply liquid under pressure to said cylinder to move said piston in one direction, and means to prevent backward flow of said liquid from said cylinder, thereby preventing movement of said piston in the opposite direction, and a pawl and ratchet device preventing rotation of said bearing in the direction opposite to that first named.

RICHARD F. DOW. 

